Suppression of KLF5 targets RREB1 to restrain the proliferation of ovarian cancer cells through ERK/MAPK signaling pathway.

Abstract

The overexpression of Kruppel-like factor 5 (KLF5) appears in several types of cancer. KLF5 may be an effective therapeutic target for treating OC, but its function in ovarian cancer (OC) remains unknown. The KLF5 mRNA expression levels in several OC cell lines were analyzed using RT-qPCR. Then, NC-siRNA or KLF5-siRNA was transfected into SK-OV-3 and OVCAR-3 cells. RT-qPCR and WB were used to detect the efficiency of KLF5 silence, CCK-8, colony formation assay, IHC staining, flow cytometry, and WB were performed to investigate the KLF5 function on OC cell proliferation and the activation of the extracellular signal-regulated Kinase (ERK)/mitogen-activated protein kinase (MAPK) signaling pathway. Next, a dual-luciferase and IF assay were used to determine the relationship between KLF5 and the Ras response element-binding protein (RREB1). SK-OV-3 and OVCAR-3 cells were treated with KLF5-siRNA and C16-PAF + EGF (MAPK agonist), separately or in combination. Proteins including KLF5, RREB1, p-p38, p-ERK1/2, ERK5, p-ERK5, Cyclin D1, CDK4, and CDK6 were quantified by WB. Finally, CCK-8, colony formation assay, and flow cytometry were employed again. KLF5 is highly expressed in OC cells compared with normal cells. When KLF5 knockdowns in SK-OV-3 and OVCAR-3 cells, the cell proliferation restrains, and the G1 phase prolongs. In addition, KLF5 silence caused a decrease of Cyclin D1, CDK4, CDK6, p-p38, p-ERK1/2, and p-ERK5/ERK5 expression levels. However, these statuses could be revised by C16-PAF + EGF. Results also found that when the ERK/MAPK signaling is activating, RREB1 is expressed low. The KLF5 silence could up-regulate the RREB1 expression. The KLF5 silence could restrain the OC cell proliferation and cell cycle. KLF5-siRNA may target upregulating RREB1 expression, thereby inhibiting the activation of the ERK/MAPK signaling pathway in OC cells.